MOSCOW — Police detained and questioned three people, including a principal Bolshoi Ballet dancer, as suspects in the acid attack that almost blinded Sergei Filin, the Bolshoi's artistic director, a crime that cast a shadow on Moscow's iconic company and exposed bitter infighting among its dancers.

Principal dancer Pavel Dmitrichenko, detained Tuesday, was reportedly suspected of masterminding the attack. Police also brought in Yuri Zarutski, 35, believed to be Filin's assailant, as well as Andrei Lipatov, a man suspected of driving Zarutski to and from the attack, according to a statement on the Interior Ministry website.

A masked assailant threw sulfuric acid at Filin outside his home Jan. 17, searing his face and neck with third-degree burns and damaging his eyesight. The attack reverberated through international ballet circles and cast a spotlight on rivalries and intrigue within the Bolshoi, one of the most prominent ballet companies in the world, whose grand theater recently reopened after renovation.

Filin is in Germany receiving treatment. He has had more than 10 surgeries, and his condition is steadily improving, Bolshoi spokeswoman Katerina Novikova said. Filin, 42, may be back to work as early as this summer, she said.

"The detainment gives us hope that the perpetrators will be found and punished," Novikova said. She added that Filin had been threatened by phone and had his Facebook account hacked before the attack, and she said she hoped authorities would find the people responsible for those acts as well.

Investigators used cellphone records to find the suspects, according to the tabloid news site Life News, citing an unidentified police source.

Police also searched Dmitrichenko's house.

One Bolshoi dancer, speaking on condition of anonymity, told The Times that Dmitrichenko's girlfriend, Anzhelina Vorontsova, had a conflict with Filin after he did not give her a coveted role.

"She was very disappointed with the way Filin treated her, not giving her the roles that she wanted," the source said.

Published reports in the last month have said that investigators were looking at dancers in the Bolshoi. Filin, who has worked at the company since 2011, was in charge of assigning roles to a troupe of 200 people.

"There were many who were satisfied with him and many who were not," Novikova said. She did not elaborate but said there was no noticeable tension in the troupe.